Depositional environment in Great Indian Desert using grain size parameters and its chemical characterization     

S.K. Wadhawan  Pankaj Kumar 《Journal of the Geological Society of India》2016,88(1):120-121

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A new find of lamproite dyke near Chintalapalle area,NW margin of the Cuddapah basin,eastern Dharwar craton,southern India     

Alok Kumar  Praveer Pankaj  K. Koteswara Rao 《Journal of the Geological Society of India》2016,87(2):127-131

A singular outcrop of a lamproite dyke is located ~1.5 km south-west of Chintalapalle village at the NW margin of the Cuddapah basin, eastern Dharwar craton, southern India.. The dyke trends E-W and is emplaced within the granitic rocks belonging to the peninsular gneissic complex. The lamproite dyke has a porphyritic to weakly porphyritic texture comprising microphenocrysts of sanidine, and potassic richterite set in a groundmass rich in carbonate, and chlorite with rutile and titanate as accessory phases. This new occurrence of lamproite is located mid-way between the well-known Narayanpet kimberlite field towards the west and the Ramadugu and Vattikod lamproite fields in east. The Chintalapalle lamproite dyke, together with those from Vattikod, Ramadugu, Krishna and Cuddapah basin lamproite fields, constitute a wide spectrum of ultrapotassic magmatism emplaced in and around the Palaeo-Mesoproterozoic Cuddapah basin in southern India.  相似文献   

Scanning sky monitor (SSM) onboard AstroSat     

M. C. Ramadevi  S. Seetha  Dipankar Bhattacharya  B. T. Ravishankar  N. Sitaramamurthy  G. Meena  M. Ramakrishna Sharma  Ravi Kulkarni  V. Chandra Babu  Kumar  Brajpal Singh  Anand Jain  Reena Yadav  S. Vaishali  B. N. Ashoka  Anil Agarwal  K. Balaji  G. Nagesh  Manoj Kumar  Dhruti Ranjan Gaan  Prashanth Kulshresta  Pankaj Agarwal  Mathew Sebastian  A. Rajarajan  D. Radhika  Anuj Nandi  V. Girish  Vivek Kumar Agarwal  Ankur Kushwaha  Nirmal Kumar Iyer 《Experimental Astronomy》2017,44(1):11-23

Scanning Sky Monitor (SSM) onboard AstroSat is an Xray sky monitor in the soft X-ray band designed with a large field of view to detect and locate transient X-ray sources and alert the astronomical community about interesting phenomena in the X-ray sky. SSM comprises position sensitive proportional counters with 1D coded mask for imaging. There are three detector units mounted on a platform capable of rotation which helps covering about 50% of the sky in one full rotation. This paper discusses the elaborate details of the instrument and few immediate results from the instrument after launch.  相似文献   

Impact of land cover change on land surface temperature: A case study of Spiti Valley     

Pankaj Kumar  Arif Husain  Ram Babu Singh  Manish Kumar 《山地科学学报》2018,15(8):1658-1670

Land surface temperature(LST) is the skin temperature of the earth surface. LST depends on the amount of sunlight received by any geographical area. Apart from sun light, LST is also affected by the land cover, which leads to change in land surface temperature. Impact of land cover change(LCC) on LST has been assessed using Landsat TM5, Landsat 8 TIRS/OLI and Digital Elevation Model(ASTER) for Spiti Valley, Himachal Pradesh, India. In the present study, Spiti valley was divided into three altitudinal zones to check the pattern of changing land cover along different altitudes and LST was calculated for all the four land cover categories extracted from remote sensing data for the years of 1990 and 2015. Matrix table was used as a technique to evaluate the land cover change between two different years. Matrix table shows that as a whole, about 2,151,647 ha(30%) area of Spiti valley experienced change in land cover in the last 25 years. The result also shows vegetation and water bodies increased by 107,560.2 ha(605.87%) and 45 ha(0.98%), respectively. Snow cover and barren land decreased by 19,016.5 ha(23.92%) and 88,589(14.14%), during the study period. A significant increase has been noticed in vegetation amongst all land cover types. Minimum, maximum and mean LST for three altitudinal zones have been calculated. The mean LST recorded was 11℃ in 1990 but it rose by 2℃ and reached to 13℃ in 2015. Changes in LST were obtained for each land cover categories. The mean temperature of different land cover types was calculated by averaging value of all pixels of a given land cover types. The mean LST of vegetation, barren land, snow cover and water body increased by 6℃, 9℃, 1℃, and 7℃, respectively. Further, relationships between LST, Normalized Difference Snow Index(NDSI), and Normalised Difference Vegetation Index(NDVI) were established using Linear Regression.  相似文献   

Nudging of vertical profiles of meteorological parameters in one-dimensional atmospheric model: A step towards improvements in numerical simulations   总被引：1，自引：0，他引：1  

D. Bala Subrahamanyam  S. Indira Rani  Radhika Ramachandran  P. K. Kunhikrishnan 《Ocean Science Journal》2008,43(4):165-173

In this article, we describe a simple yet effective method for insertion of observational datasets in a mesoscale atmospheric model used in one-dimensional configuration through Nudging. To demonstrate the effectiveness of this technique, vertical profiles of meteorological parameters obtained from GLASS Sonde launches from a tiny island of Kaashidhoo in the Republic of Maldives are injected in a mesoscale atmospheric model — Advanced Regional Prediction System (ARPS), and model simulated parameters are compared with the available observational datasets. Analysis of one-time nudging in the model simulations over Kaashidhoo show that incorporation of this technique reasonably improves the model simulations within a time domain of +6 to +12 Hrs, while its impact on +18 Hrs simulations and beyond becomes literally null.  相似文献   

Characterization of meteorological drought over a dryland ecosystem in north western India     

Singh  Omvir  Saini  Divya  Bhardwaj  Pankaj 《Natural Hazards》2021,106(1):785-804

Natural Hazards - Fatal landslides cause severe disasters to human lives and socioeconomic costs in China. In this study, the data non-seismically fatal landslides were collected between 2004 and...  相似文献   

Long-Term Variability of Nutrients and Chlorophyll in the Chesapeake Bay: A Retrospective Analysis, 1985–2008     

M. Bala Krishna Prasad  Mathew R. P. Sapiano  Clarissa R. Anderson  Wen Long  Raghu Murtugudde 《Estuaries and Coasts》2010,33(5):1128-1143

A retrospective analysis of freshwater discharge, riverine dissolved nutrient loads, dissolved nutrients, and chlorophyll in the Chesapeake Bay from 1985 to 2008 is presented. It is evident that each field displays an interannual variability averaged over the Bay. The N and P loads peaked in 1997 and have fluctuated with a decreasing trend since early 2004. Dissolved nutrient concentrations in the Bay appear to be largely controlled by riverine nutrient loads. The temporal variability of chlorophyll is positively correlated with nutrient loads and concentrations. Over the study period, N:P (DIN:DIP) molar ratios were consistently higher than the Redfield ratio (N:P?=?16:1) and strongly correlated with river discharge (R ²?=?0.68, p??16:1), and N is the limiting nutrient in summer and early autumn (N:P?4 from anoxic sediments. Long-term climate indices, such as El Niño Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO), appear to exert only a moderate control over the riverine discharge to the Bay or over the ecosystem response in terms of chlorophyll in the Bay. While not all related mechanisms can be inferred from available data, this analysis should help in determining future data needs for monitoring water quality and human and climate influence on the health of the Bay.  相似文献   

Geochemistry,zircon UPb ages and Hf isotopes of granites and pegmatites from Gubrunde region in the Eastern Nigeria Terrane: Insight into magmatism and tectonic evolution of the late Pan-African orogeny     

Saleh Ibrahim Bute  Xiaoyong Yang  Xueming Yang  Musa Bala Girei  Amuda Abdulgafar Kayode  Yigan Lu 《Chemie der Erde / Geochemistry》2022,82(1):125809

This study reports a new dataset of whole-rock geochemistry, biotite chemistry, in situ zircon UPb geochronology and Hf isotope for a suite of granite and associated pegmatite samples from the Gubrunde region in the Eastern Nigeria Terrane (ENT), Nigeria. The Gubrunde granitic rocks are weakly ferroan, peraluminous and calc-alkalic to alkali-calcic in composition, and show I-type affinity. The zircon UPb geochronology gives an age of ~580 Ma for the rocks, although the presence of inherited zircons with early Pan-African ages of 696 ± 12, 647 ± 7 and 624–613 Ma are evident indicative of a complex history of their source rocks. The Gubrunde granite and the pegmatite yielded similar average Hf crustal model age T_DM2 of 1.9 ± 0.1 Ga and εHf(t) values ?6.2 ± 1.2, suggesting that they may have sourced from reworked old crustal rocks with minor contributions from the mantle. The granite and the pegmatite were likely to connect by fractional crystallization under low to moderate pressure (~2.2 to 3.0 kbar) and temperature (~717 °C), and low oxygen fugacity (<ΔNNO ?1.14). The ca. 580 Ma magmatism may have been triggered by delamination of the lithospheric mantle as a consequence of crustal thinning during waning stage of the Pan-African orogeny.  相似文献   

Variability of Mixed-Layer Heights over the Indian Ocean and Central Arabian Sea during INDOEX, IFP-99     

D. Bala Subrahamanyam  Radhika Ramachandran  K. Sen Gupta  Tuhin K. Mandal 《Boundary-Layer Meteorology》2003,107(3):683-695

The upper air data collected from the balloon-borne GLASS Sondes launched from the Oceanic Research Vessel (ORV) Sagar Kanya during the Intensive Field Phase of the Indian Ocean experiment (INDOEX, IFP-99;SK-141 Cruise) are utilized forstudying the variability in the mixed-layer heights observed over the western tropical Indian Ocean and central Arabian Sea. During the entire cruise, typical daytime convective mixed-layer heights (roughly corresponding to 1400 LT) obtained from _V and q profiles, were observed to be in the range 200–900 m. Shallowmixed -layer heights are observed, in general, over the Inter-Tropical Convergence Zone (ITCZ). Over the central Arabian Sea, vertical profiles of _V and q demonstrate a double mixed-layer structure of the marine atmospheric boundary layer (MABL), which gradually disappears close to the Indian coastline.  相似文献   

用于油藏描述的三维地质体剖分及体积计算方法   总被引：3，自引：0，他引：3  

刘劲松  许云 《现代地质》1997,11(2):217-220

针对计算机模拟中的关键问题，即三维地质体的剖分和体积计算方法进行了较深入的讨论。在将地质体剖分为内部单元和边缘单元之后，又将内部单元细分为中间的长方柱体和两端的不规则多面体。通过分析，给出了计算内部单元和边缘单元不规则多面体的体积计算公式，并通过对两种理论模型的剖分和计算结果，说明了方法的正确性和提高精度的有效性  相似文献